Alright, let's try and puzzle out this riddle step by step using logic and reasoning.
As stated in the riddle, the object or thing that we're looking for is born in water and spends its life in water. However, the catch is, despite being from and existing in water, it will 'die' or cease to exist if thrown in water.
Considering the clues, the term 'born in water' might imply something produced or formed in water. Pondering on this fact, the only logical thing that comes to mind is 'salt', as it's formed in seawater.
The second clue says that it 'lives in water'. Salt indeed stays in solution or acts as an integral part of water once it has been mixed or dissolved in it. Thus, salt 'lives' in water.
Now, the final part of the riddle states that if you throw it in water, it will die. This is true for salt because when salt is stirred into water, it disappears or ‘dies’ because it has been dissolved. It seems counter-intuitive to think of salt dying in water because it’s where it comes from, but dying here means it no longer exists in its original solid form as it has become part of the water.
So, based on the given facts and after careful consideration of the clues, we can determine the answer to the riddle, "I am born in water, I live in water, but if you throw me in water, I will die" is "a salt."